1. Field of the Invention
The present invention relates to telescoping stacking conveyors. More specifically, the invention provides a telescoping radial stacking conveyor having a single conveyor belt, operated by a single drive mechanism.
2. Description of the Related Art
Radial stacking conveyors are typically used to transport material into stockpiles, storage bins, or other storage locations. Portable radial stacking conveyors are presently designed so that they include folding ends to shorten the length of the stacker for transportation, or are telescoping for the same reason. They typically include a conveyor frame or boom driven by an undercarriage having a wheel assembly. The conveyor includes means for raising and lowering the boom, and means for pivoting the boom about the tail end of the conveyor.
An example of a portable radial stacker is disclosed in U.S. Pat. No. 4,135,614, issued to L. F. Penterman et al. on Jan. 23, 1979. The stacker includes an axle assembly having a transverse member secured to the end of the supporting structure of the stacker. A torsion lever is pivotally secured to each end of the transverse member, and has a pair of tires, with each tire having an independent suspension mounting at its other end. The torsion levers may be pivoted from a position wherein they are aligned with the transverse member, to a position wherein they are substantially perpendicular to the transverse member.
U.S. Pat. No. 4,427,104, issued to E. W. Reid, Jr. on Jan. 24, 1984, discloses a folding radial stacker. The stacker includes a central portion and a pair of end portions. Each end portion is pivotally secured to one end of the central portion. An A-shaped frame is pivotally secured at the hinge between each end portion and the central portion. At each end, the hydraulic ram extends from the central portion to the A-shaped portion, and from the A-shaped portion to the end portion.
U.S. Pat. No. 5,390,777, issued to P. G. Gage on Feb. 21, 1995, discloses a constant pivot mechanism for variable height radial stacking conveyors. The mechanism includes a curved channel through which the top of the rear push arm travels as the conveyor is raised and lowered.
U.S. Pat. No. 5,515,961, issued to R. B. Murphy et al. on May 14, 1996, discloses a portable radial stacking conveyor. The stacker uses hydraulic fold-down outriggers having radial travel wheels at their ends. When the outriggers are lowered, the transport wheels are raised. A similar radial stacker is described in U.S. Pat. No. 5,833,043, issued to P. Schmidgall et al. on Nov. 10, 1998.
U.S. Pat. No. 6,056,252, issued to T. J. Johannsen on May 2, 2000, discloses a support assembly for a telescopic conveyor system. The support assembly includes a pivot plate connected to the base frame, and including first and second bearing plates, each pivotally secured to the pivot plate. Each of the bearing plates is located on opposite sides of the pivot plate. The support rollers support the extendable frame, thereby facilitating extension and retraction of the extendable frame, with the weight of the extendable frame proportionally distributed over all of the support rollers. Both the base frame and extendable frame include a conveyor belt.
U.S. Pat. No. 6,360,876, issued to J. D. Nohl et al. on Mar. 26, 2002, discloses a portable telescoping radial stacking conveyor. The conveyor includes a base and extendable portion, called a stinger, each of which has its own conveyor belt with its own drive mechanism. A winch mechanism is used to extend and retract the stinger from the base. The base includes transport wheels and a pair of outriggers having radial wheels. During transportation, the outriggers are raised so that the base rests on the transport wheels. During use, the outriggers are lowered, raising the transport wheels off the ground, and permitting the conveyor to pivot around one end of the base. Extension and retraction of the stinger, and radial movement of the conveyor, may be accomplished manually or by an automatic control system during a stacking operation.
Telescoping conveyors have the advantage of stacking material at any desired distance from the base within the minimum retracted and maximum extended position of the stinger. Fixed length or folding conveyors may only deposit material at a single, fixed distance from the base. However, telescoping conveyors typically include a pair of conveyor belts, with one conveyor being located on the base, and the other being located on the stinger, and with each conveyor having a separate drive mechanism. It is therefore necessary to maintain two separate drive mechanisms. The drive mechanism of the stinger is often located at the terminal end of the stinger, increasing the difficulty of servicing this mechanism. This location is often required, because the terminal end of the stinger is the only part accessible through the main frame with the stinger retracted. Accordingly, it is desirable to provide a telescoping portable radial stacking conveyor having a single conveyor belt, operated by a single drive mechanism.